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Date: Mon, 25 Aug 1997 22:13:35 -0700 (PDT)
From: Julian Elischer <julian@whistle.com>
To: Greg Lehey <grog@lemis.com>
cc: Mike Smith <mike@smith.net.au>,
        Joerg Wunsch <joerg_wunsch@uriah.heep.sax.de>,
        "hackers@freebsd.org" <hackers@FreeBSD.ORG>,
        Mike Burgett <mburgett@awen.com>
Subject: Re: special malloc needs...
In-Reply-To: <19970826133233.19386@lemis.com>
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There is only one way I can think of doing what is requested..

write a silly little pseudo device that allocates a couple of meg
of physical contig ram at startup

mmap it into your address space..


On Tue, 26 Aug 1997, Greg Lehey wrote:

> On Tue, Aug 26, 1997 at 01:22:50PM +0930, Mike Smith wrote:
> >> On Mon, Aug 25, 1997 at 10:20:08PM +0200, J Wunsch wrote:
> >>> As Mike Burgett wrote:
> >>>
> >>>> Is there any way to malloc memory (from userland code) that is at
> >>>> specific offsets from each other in physical memory (i.e. 2 chunks
> >>>> exactly XXM apart in physical RAM) or failing that, to allocate a
> >>>> very large (>32M) chunk of contig physical RAM? (again, from
> >>>> userland?)
> >>>
> >>> No, you can't do this.  You get virtual memory, nothing else.  It's
> >>> not even backed with physical memory at all when you've got it.
> >>
> >> Well, you can't malloc() it, but you can try to mmap() it with
> >> MAP_FIXED.  man mmap(2).
> >
> > This only gives you a fixed _virtual_ address.
> 
> Yes, it does.  That's what I thought he wanted.  Re-reading the
> original message, I see I was wrong.  Mike (B), whatever do you want
> to allocate physical memory for?
> 
> Greg
>